Use of a composition containing at least one oxidation-sensitive hydrophilic active principle and at least one N-vinylimidazole polymer or copolymer

ABSTRACT

The invention relates to the use of a composition contains at least one oxidation-sensitive hydrophilic active principle selected from the group consisting of ascorbic acid and its derivatives and at least one non-crosslinked N-vinylimidazole polymer or copolymer, the active principle and the said polymer or copolymer both being in the aqueous phase, for lightening and/or depigmenting the skin and/or hair, including body hair.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to the use of a compositioncomprising at least one oxidation-sensitive hydrophilic active principleand at least one N-vinylimidazole polymer or copolymer, preferably in aphysiologically acceptable medium comprising an aqueous phase.Preferably the use is a cosmetic and/or dermatological use related tolightening or depigmenting the skin and/or the hair, and is thuspreferably targeted to skin and/or hair to be lightened.

[0003] 2. Background of the Invention

[0004] It is known to introduce, into cosmetic compositions, variousactive principles intended to contribute specific treatments to the skinand/or hair. However, some of these active principles exhibit thedisadvantage of being unstable in an aqueous medium and of easilydecomposing on contact with water, in particular because of oxidationphenomena. They thus rapidly lose their activity over time and thisinstability conflicts with the desired effectiveness.

[0005] Attempts have thus been made for a long time to formulateascorbic acid or vitamin C because of its numerous beneficialproperties. In particular, ascorbic acid stimulates the synthesis of theconnective tissue and in particular of collagen, strengthens thedefences of the cutaneous tissue against external attacks, such asultraviolet radiation and pollution, compensates for vitamin Edeficiency of the skin, depigments the skin and has a role in combattingfree radicals. These last two properties make it an excellent candidateas cosmetic or dermatological active principle for combatting ageing ofthe skin or for preventing ageing of the skin. Unfortunately, because ofits chemical structure (of α-ketolactone), ascorbic acid is highlysensitive to certain environmental parameters and in particular tooxidation phenomena. There thus ensues rapid decomposition of formulatedascorbic acid in the presence of these parameters and in particular inthe presence of oxygen, light or metal ions, as a function of thetemperature or under certain pH conditions (Pharm. Acta. Helv., 1969,44, 611-667; STP Pharma, 1985, 4, 281-286).

[0006] Several solutions have thus been envisaged in the prior art forreducing and/or slowing down the decomposition of ascorbic acid.

[0007] Provision has thus been made to use ascorbic acid in the form ofa chemical derivative (magnesium ascorbyl phosphate or esters of fattyacids and ascorbic acid), but the bioavailability of these derivativesis very low (J. Am. Acad. Dermatol., 1996, 34, 29-33).

[0008] The instability of ascorbic acid with respect to oxygen can beimproved by using specific packagings, such as twin compartments underan inert atmosphere, as disclosed in U.S. Pat. No. 5,935,584, oralternatively by the use of two-phase emulsions, one phase of which iscomposed of a dry powder comprising ascorbic acid and the second phaseof which is a liquid phase. The mixing of the two phases has to becarried out at the time of use (WO 98/43598). These solutions havedisadvantages with regard to the cost and the complexity of themanufacturing operations and significant restrictions with regard touse.

[0009] Another solution provided in the prior art consists in using ahigh concentration of glycols or polyols in order to reduce thesolubility of oxygen in the formulation, thus protecting the ascorbicacid (WO 96/24325, EP 0 755 674, U.S. Pat. No. 5,981,578). The polyolscan optionally be incorporated in liposomes, as disclosed in U.S. PatNo. 6,020,367. However, these solutions exhibit the disadvantage ofresulting in sticky formulations, the cosmetic quality of which isdifficult to improve. Furthermore, the presence of a high concentrationof these compounds can lead to phenomena of irritation.

[0010] Ascorbic acid can also be formulated in anhydrous media, such assilicones (U.S. Pat. No. 6,194,452), which are capable of creating ananhydrous barrier around ascorbic acid. A major disadvantage of suchsolutions results from the lack of freshness on application.

[0011] The need thus remains for a composition employable in particularin the cosmetics field, in which a hydrophilic active principle which isunstable in an oxidizing medium is stabilized, which is comfortable onapplication, which does not lead to any skin irritation afterapplication and which is compatible with the constraints of anindustrial implementation of its manufacturing process.

[0012] The activity of ascorbic acid or of its derivatives onpigmentation has been known for many years. Various mechanisms have beendescribed to explain their effect on the reduction of melanogenesis. Theinhibiting effect on tyrosinase has been demonstrated for ascorbic acid(J. Soc. Cosmet. Chem., 42, 1991, p. 361-368). Some of its esters havebeen used for some years in depigmenting treatments, that is to say,magnesium ascorbyl phosphate and ascorbyl glucoside. More recently, astudy has shown that magnesium ascorbyl phosphate can reduce thedendricity of melanocytes (Pigment. Cell. Res., 13, 2000, p. 89-98 andp. 190-192).

OBJECTS OF THE INVENTION

[0013] One object of the present invention is to provide a compositioncomprising an oxidation-sensitive active principle selected from thegroup consisting of ascorbic acid and its derivatives, which exhibitsgood cosmetic properties, both with regard to touch and with regard totolerance, the preservation of which over time does not require specificprecautions, and which retains the depigmenting and/or lighteningability of the active principle.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The Inventors have discovered that the use of non-crosslinkedN-vinylimidazole polymers or copolymers in compositions in which theaqueous phase includes an oxidation-sensitive active principle, such asascorbic acid, makes it possible to achieve the abovementioned object.

[0015] In the prior art, some compounds having an imidazole structurehave been disclosed for their stabilizing properties. Thus, in PatentApplication EP 0 586 106, several imidazole-based molecules are used tostabilize certain retinoids against chemical decomposition. Furthermore,polymeric emulsifiers composed of N-vinylimidazole, of alkyl acrylatesand of vinyl acetates are disclosed in U.S. Pat. No. 4,057,622. They areused for the purpose of replacing known emulsifiers in order to overcometheir disadvantages, in particular with regard to smell, and tostabilize water-in-oil emulsions. Finally,N-vinylimidazole/N-vinylcaprolactam/N-vinylpyrrolidone copolymers aredisclosed in U.S. Pat. No. 6,191,188. They are used in the manufactureof hair-strengthening compositions.

[0016] To the knowledge of the inventors, polymers or copolymerscomprising N-vinylimidazole units have never been used in combinationwith hydrophilic active principles sensitive to decomposition byoxidation for the purpose of improving their stability in an aqueousmedium. This is true in particular in the case of ascorbic acid.

[0017] One embodiment of the present invention is therefore thepreferably cosmetic and/or dermatological use of a composition fordepigmenting and/or lightening the skin and/or hair, including bodyhair, the composition comprising, preferably in a physiologicallyacceptable medium comprising an aqueous phase, at least oneoxidation-sensitive hydrophilic active principle selected from the groupconsisting of ascorbic acid and its derivatives and at least onenon-crosslinked N-vinylimidazole polymer or copolymer, the activeprinciple and the polymer or copolymer both being present in the aqueousphase. The copolymer is preferably present in an amount sufficient tostabilize the said oxidation-sensitive hydrophilic active principle.

[0018] The use of such a composition furthermore exhibits the advantageof acting both by inhibiting tyrosinase, thus reducing melanogenesis,and also by inhibiting the dendricity of melanocytes. The depigmentingeffect thus obtained is much greater than that obtained, for example,with ascorbic acid alone, which acts solely on melanogenesis.

[0019] Another embodiment of the present invention is the use of acombination composed of at least one oxidation-sensitive hydrophilicactive principle selected from the group consisting of ascorbic acid andits derivatives and of at least one non-crosslinked N-vinylimidazolepolymer or copolymer, the active principle and the polymer or copolymerboth being in the aqueous phase, in a cosmetic composition, asdepigmenting agent.

[0020] According to the invention, the term “hydrophilic activeprinciple” is understood to mean a compound having a solubility in waterof at least 0.25% at ambient temperature (25° C.).

[0021] According to the invention, the term “oxidation-sensitivehydrophilic active principle” is understood to mean any active principleof natural or synthetic origin capable of undergoing decomposition by anoxidation mechanism. This oxidation phenomenon can have several causes,in particular the presence of oxygen, of light or of metal ions, a hightemperature or certain pH conditions.

[0022] Mention may be made, by way of example and without impliedlimitation, of: ascorbic acid and its derivatives, such as salts andesters thereof, particularly the 5,6-di-O-dimethylsilylascorbate (soldby Exsymol under the reference PRO-AA), the potassium salt ofdl-α-tocopheryl dl-ascorbyl phosphate (sold by Senju Pharmaceuticalunder the reference SEPIVITAL EPC), magnesium ascorbyl phosphate orsodium ascorbyl phosphate (sold by Roche under the reference Stay-C 50).

[0023] In a particularly advantageous aspect, the oxidation-sensitivehydrophilic active principle is ascorbic acid. Other preferredprinciples meet the above requirements and possess the ability tolighten the skin and/or the hair.

[0024] The oxidation sensitive hydrophilic active principle ispreferably present in an amount sufficient to lighten the hair and/orskin, which amount is determinable by one of ordinary skill withoutundue effort. Example amounts include 1-10% based on total weight.

[0025] According to the invention, the term “non-crosslinkedN-vinylimidazole polymer or copolymer” is understood to mean any polymercomprising N-vinylimidazole units and not comprising a crosslinkingagent. Copolymers suitable for the implementation of the invention arecopolymers combining N-vinylimidazole with N-vinylpyrrolidone and/orN-vinylcaprolactam subunits.

[0026] In an advantageous aspect of the invention, the copolymer has amolar fraction of N-vinylimidazole units of between 0.1 and 1, morepreferably between 0.4 and 0.9.

[0027] According to an advantageous aspect of the invention, the molarratio of the N-vinylimidazole unit equivalent to the oxidation-sensitivehydrophilic active principle varies between 0.004 and 16 and preferablybetween 0.01 and 1.

[0028] Use is preferably made of an N-vinylimidazole/N-vinylpyrrolidonecopolymer.

[0029] The weight-average molar mass of the N-vinylimidazole polymers ispreferably between 1 000 and 1×10⁷ and more preferably between 5 000 and5×10⁶.

[0030] Use may be made, to this end, of thevinylpyrrolidone/vinylimidazole (50/50) copolymer having aweight-average molar mass of 1 200 000 sold under the reference LUVITECVPI 55K72W by BASF or the vinylpyrrolidone/vinylimidazole (50/50)copolymer having a weight-average molar mass of 10 000 sold under thereference LUVITEC VPI 55K18P by BASF. The polymers or copolymersaccording to the invention can, for example, be prepared according tothe method disclosed in Patent Application WO-97/45517.

[0031] The at least one polymer or copolymer is preferably present inthe composition according to the invention in an amount sufficient toproduce the desired effect, that is to say in an amount sufficient tostabilize the oxidation-sensitive hydrophilic active principle.Preferably, the polymer or copolymer is present at a concentration ofbetween 0.1 and 5% by weight with respect to the total weight of theaqueous phase and more particularly at a concentration of between 0.1and 2% by weight with respect to the total weight of the aqueous phase.

[0032] The compositions used according to the invention are preferablyintended for topical application to the skin and/or its superficial bodygrowths and therefore comprise a physiologically acceptable medium, thatis to say a medium compatible with cutaneous tissues, such as the skin,scalp, eyelashes, eyebrows, hair, nails and mucous membranes. Thisphysiologically acceptable medium comprises at least one aqueous phaseand optionally a physiologically acceptable organic solvent chosen, forexample, from lower alcohols comprising from 1 to 8 carbon atoms and inparticular from 1 to 6 carbon atoms, such as ethanol, isopropanol,propanol or butanol; polyethylene glycols having from 6 to 80 ethyleneoxide units; or polyols, such as propylene glycol, isoprene glycol,butylene glycol, glycerol or sorbitol.

[0033] When the physiologically acceptable medium is an aqueous medium,it generally has a pH which is compatible with the skin, preferablyranging from 3 to 9 and better still from 3.5 to 7.5.

[0034] The compositions according to the invention can be provided inany form, including any pharmaceutical dosage form used for topicalapplication and in particular in the form of aqueous oraqueous/alcoholic solutions, of oil-in-water (O/W) or water-in-oil (W/O)or multiple (triple: W/O/W or O/W/O) emulsions, of aqueous gels or ofdispersions of a fatty phase in an aqueous phase using spherules, itbeing possible for these spherules to be polymeric nanoparticles, suchas nanospheres and nanocapsules, or lipid vesicles of ionic and/ornonionic type (liposomes, niosomes or oleosomes). These compositions areprepared according to the usual methods.

[0035] In addition, the compositions used according to the invention canbe more or less fluid and can have the appearance of a white or colouredcream, of an ointment, of a milk, of a lotion, of a serum, of a paste orof a foam. They can optionally be applied to the skin in the form of anaerosol. They can also be provided in a solid form, for example in theform of a stick.

[0036] When the composition used according to the invention comprises anoily phase, the latter preferably comprises at least one oil. It canadditionally comprise other fatty substances.

[0037] Mention may be made, as oils which can be used in the compositionof the invention, of, for example:

[0038] hydrocarbonaceous oils of animal origin, such asperhydrosqualene;

[0039] hydrocarbonaceous oils of vegetable origin, such as liquidtriglycerides of fatty acids comprising from 4 to 10 carbon atoms, suchas triglycerides of heptanoic acid or octanoic acid, or alternatively,for example, sunflower, maize, soybean, gourd, grape seed, sesame,hazelnut, apricot, macadamia, arara, castor or avocado oils,triglycerides of caprylic/capric acids, such as those sold byStéarineries Dubois or those sold under the names Miglyol 810, 812 and818 by Dynamit Nobel, jojoba oil, or karite butter oil;

[0040] synthetic esters and ethers, in particular of fatty acids, suchas the oils of formulae R¹COOR² and R¹OR² in which R¹ represents theresidue of a fatty acid comprising from 8 to 29 carbon atoms and R²represents a branched or unbranched hydrocarbonaceous chain comprisingfrom 3 to 30 carbon atoms, such as, for example, purcellin oil, isononylisononanoate, isopropyl myristate, 2-ethylhexyl palmitate,2-octyldodecyl stearate, 2-octyldodecyl erucate or isostearylisostearate; hydroxylated esters, such as isostearyl lactate, octylhydroxystearate, octyldodecyl hydroxystearate, diisostearyl malate,triisocetyl citrate or heptanoates, octanoates or decanoates of fattyalcohols; polyol esters, such as propylene glycol dioctanoate, neopentylglycol diheptanoate and diethylene glycol diisononanoate; andpentaerythritol esters, such as pentaerythrityl tetraisostearate;

[0041] linear or branched hydrocarbons of mineral or synthetic origin,such as volatile or nonvolatile liquid paraffins and their derivatives,liquid petrolatum, polydecenes or hydrogenated polyisobutene, such asparleam oil;

[0042] fatty alcohols having from 8 to 26 carbon atoms, such as cetylalcohol, stearyl alcohol and their mixture (cetearyl alcohol),octyldodecanol, 2-butyloctanol, 2-hexyldecanol, 2-undecylpentadecanol,oleyl alcohol or linoleyl alcohol;

[0043] partially hydrocarbon-comprising and/or silicone-comprisingfluorinated oils, such as those disclosed in the document JP-A-2-295912;

[0044] silicone oils, such as volatile or nonvolatilepolymethylsiloxanes (PDMS) comprising a linear or cyclic silicone chainwhich are liquid or pasty at ambient temperature, in particularcyclopolydimethylsiloxanes (cyclomethicones), such as cyclohexasiloxane;polydimethylsiloxanes comprising pendent alkyl, alkoxy or phenyl groupsor alkyl, alkoxy or phenyl groups at the end of the silicone chain,which groups have from 2 to 24 carbon atoms; or phenylated silicones,such as phenyl trimethicones, phenyl dimethicones,phenyltrimethylsiloxydiphenylsiloxanes, diphenyl dimethicones,diphenylmethyldiphenyltrisiloxanes,(2-phenylethyl)trimethylsiloxysilicates and polymethylphenylsiloxanes;

[0045] their mixtures.

[0046] The term “hydrocarbonaceous oil” is understood to mean, in thelist of the oils mentioned above, any oil predominantly comprisingcarbon and hydrogen atoms and optionally ester, ether, fluorinated,carboxylic acid and/or alcohol groups.

[0047] The other fatty substances which can be present in the oily phaseare, for example, fatty acids comprising from 8 to 30 carbon atoms, suchas stearic acid, lauric acid, palmitic acid and oleic acid; waxes, suchas lanolin, beeswax, carnauba or candelilla wax, paraffin or lignitewaxes or microcrystalline waxes, ceresin or ozokerite, or syntheticwaxes, such as polyethylene waxes or Fischer-Tropsch waxes; siliconeresins, such as trifluoromethyl C₁₋₄ alkyl dimethicone andtrifluoropropyl dimethicone; and silicone elastomers, such as theproducts sold under the names “KSG” by Shin-Etsu, under the names“Trefil”, “BY29” or “EPSX” by Dow Corning or under the names “Gransil”by Grant Industries.

[0048] These fatty substances can be chosen in a way varied by a personskilled in the art in order to prepare a composition having the desiredproperties, for example of consistency or of texture, in view of thisdisclosure.

[0049] According to a specific embodiment of the invention, thecomposition according to the invention is a water-in-oil (W/O) oroil-in-water (O/W) emulsion. The proportion of the oily phase in theemulsion can range from 5 to 80% by weight and preferably from 5 to 50%by weight with respect to the total weight of the composition.

[0050] The emulsions generally preferably comprise at least oneemulsifier selected from the group consisting of amphoteric, anionic,cationic or nonionic emulsifiers, used alone or as a mixture, andoptionally a coemulsifier. The emulsifiers are appropriately chosenaccording to the emulsion to be obtained (W/O or O/W). The emulsifierand the coemulsifier are generally preferably present in the compositionin a proportion ranging from 0.3 to 30% by weight and preferably from0.5 to 20% by weight with respect to the total weight of thecomposition.

[0051] Mention may be made, for the W/O emulsions, for example, asemulsifiers, of dimethicone copolyols, such as the mixture ofcyclomethicone and of dimethicone copolyol sold under the name “DC 5225C” by Dow Corning, and alkyl dimethicone copolyols, such as thelaurylmethicone copolyol sold under the name “Dow Corning 5200Formulation Aid” by Dow Coming and the cetyl dimethicone copolyol soldunder the name Abil EM 90^(R) by Goldschmidt. Use may also be made, assurfactant of W/O emulsions, of a crosslinked solid organopolysiloxaneelastomer comprising at least one oxyalkylenated group, such as thoseobtained according to the procedure of Examples 3, 4 and 8 of thedocument U.S. Pat. No. 5,412,004 and the examples of the document U.S.Pat. No. 5,811,487, in particular the product of Example 3 (syntheticexample) of U.S. Pat. No. 5,412,004, and such as that sold under thereference KSG 21 by Shin Etsu. Use may also be made, as emulsifier, of apolyolefin-derived oligomer or polymer comprising a succinic ending; thelatter is preferably a polyolefin comprising an esterified or amidatedsuccinic ending or a salt of such a polyolefin and in particularpolyisobutylene comprising an esterified or amidated succinic endingsuch as the products sold under the names L5603 and L2721 and OS131769by Lubrizol.

[0052] Mention may be made, for the O/W emulsions, for example, asemulsifiers, of nonionic emulsifiers, such as esters of fatty acids andof glycerol which are oxyalkylenated (more particularlypolyoxyethylenated); esters of fatty acids and of sorbitan which areoxyalkylenated; esters of fatty acids which are oxyalkylenated(oxyethylenated and/or oxypropylenated); ethers of fatty alcohols whichare oxyethylenated (oxyethylenated and/or oxypropylenated); sugaresters, such as sucrose stearate; and their mixtures, such as themixture of glyceryl stearate and of PEG-40 stearate.

[0053] The cosmetic or dermatological composition of the invention canalso comprise adjuvants known in the cosmetics or dermatological field,such as hydrophilic or lipophilic gelling agents, preservatives,solvents, fragrances, fillers, UV screening agents, bactericides, odourabsorbers, colouring materials, plant extracts or salts. The amounts ofthese various adjuvants are those generally used in the field underconsideration, for example from 0.01 to 20% of the total weight of thecomposition. These adjuvants, depending on their nature, can beintroduced into the fatty phase, into the aqueous phase and/or into thelipid spherules.

[0054] Mention may be made, as fillers which can be used in thecomposition of the invention, for example, of pigments, silica powder;talc; particles of polyamide and in particular those sold under the nameOrgasol by Atochem; polyethylene powders; microspheres based on acryliccopolymers, such as those made of ethylene glycol dimethacrylate/laurylmethacrylate copolymer which are sold by Dow Corning under the namePolytrap; expanded powders, such as hollow microspheres and inparticular the microspheres sold under the name Expancel by KemanordPlast or under the name Micropearl F 80 ED by Matsumoto; silicone resinmicrobeads, such as those sold under the name Tospearl by ToshibaSilicone; and their mixtures. These fillers can be present in amountsranging from 0 to 20% by weight and preferably from 1 to 10% by weightwith respect to the total weight of the composition.

[0055] According to a preferred embodiment, the compositions inaccordance with the invention can additionally comprise at least oneorganic photoprotective agent and/or at least one inorganicphotoprotective agent which is active in the UV-A and/or UV-B regions(absorbers), and which are soluble in water or in fats or else areinsoluble in the cosmetic solvents commonly used.

[0056] The organic photoprotective agents are chosen in particular fromanthranilates; cinnamic derivatives; dibenzoylmethane derivatives;salicylic derivatives; camphor derivatives; triazine derivatives, suchas those disclosed in Patent Applications U.S. Patent No. 4,367,390, EP863 145, EP 517 104, EP 570 838, EP 796 851, EP 775 698, EP 878 469, EP933 376, EP 507 691, EP 507 692, EP 790 243 and EP 944 624; benzophenonederivatives; β,β-diphenylacrylate derivatives; benzotriazolederivatives; benzalmalonate derivatives; benzimidazole derivatives;imidazolines; bisbenzoazolyl derivatives as disclosed in Patents EP 669323 and U.S. Pat. No. 2,463,264; p-aminobenzoic acid (PABA) derivatives;methylenebis(hydroxyphenylbenzotriazole) derivatives as disclosed inApplications U.S. Pat. No. 5,237,071, U.S. Pat. No. 5,166,355, GB 2 303549, DE 197 26 184 and EP 893 119; screening polymers and screeningsilicones, such as those disclosed in particular in Application WO93/04665; dimers derived from α-alkylstyrene, such as those disclosed inPatent Application DE 198 55 649; 4,4-diarylbutadienes as disclosed inApplications EP 0 967 200, DE 197 46 654, DE 197 55 649, EP-A-1 008 586,EP 1 133 980 and EP 133 981; and their mixtures.

[0057] By way of illustration, mention may be made, as photoprotectiveagents which are active in the UV-A and/or UV-B regions, denoted belowunder their INCI names, of:

[0058] p-aminobenzoic acid (PABA) derivatives, in particular PABA, ethylPABA, ethyl dihydroxypropyl PABA, ethylhexyl dimethyl PABA (sold inparticular under the name “Escalol 507” by ISP), glyceryl PABA or PEG-25PABA (sold under the name “Uvinul P25” by BASF),

[0059] salicylic derivatives, in particular homosalate (sold under thename “Eusolex HMS” by Rona/EM Industries), ethylhexyl salicylate (soldunder the name “Neo Heliopan OS” by Haarmann and Reimer), dipropyleneglycol salicylate (sold under the name “Dipsal” by Scher), or TEAsalicylate (sold under the name “Neo Heliopan TS” by Haarmann andReimer),

[0060] dibenzoylmethane derivatives, in particular butylmethoxydibenzoylmethane (sold in particular under the trade name “Parsol1789” by Hoffmann-LaRoche), or isopropyl dibenzoylmethane,

[0061] cinnamic derivatives, in particular ethylhexyl methoxycinnamate(sold in particular under the trade name “Parsol MCX” byHoffmann-LaRoche), isopropyl methoxycinnamate, isoamyl methoxycinnamate(sold under the trade name “Neo Heliopan E 1000” by Haarmann andReimer), cinoxate, DEA methoxycinnamate, diisopropyl methyl cinnamate,or glyceryl ethylhexanoate dimethoxycinnamate,

[0062] β,β-diphenylacrylate derivatives, in particular octocrylene (soldin particular under the trade name “Uvinul N539” by BASF) or etocrylene(sold in particular under the trade name “Uvinul N35” by BASF),

[0063] benzophenone, in particular benzophenone-1 (sold under the tradename “Uvinul 400” by BASF), benzophenone-2 (sold under the trade name“Uvinul D50” by BASF), benzophenone-3 or oxybenzone (sold under thetrade name “Uvinul M40” by BASF), benzophenone-4 (sold under the tradename “Uvinul MS40” by BASF), benzophenone-5, benzophenone-6 (sold underthe trade name “Helisorb 11” by Norquay), benzophenone-8 (sold under thetrade name “Spectra-Sorb UV-24” by American Cyanamid), benzophenone-9(sold under the trade name “Uvinul DS-49” by BASF), benzophenone-12, orn-hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate,

[0064] benzylidene camphor derivatives, in particular 3-benzylidenecamphor (manufactured under the name “Mexoryl SD” by Chimex),4-methylbenzylidene camphor (sold under the name “Eusolex 6300” byMerck), benzylidene camphor sulphonic acid (manufactured under the name“Mexoryl SL” by Chimex), camphor benzalkonium methosulphate(manufactured under the name “Mexoryl SO” by Chimex), terephthalylidenedicamphor sulphonic acid (manufactured under the name “Mexoryl SX” byChimex), or polyacrylamidomethyl benzylidene camphor (manufactured underthe name “Mesoryl SW” by Chimex),

[0065] benzimidazole derivatives, in particular phenylbenzimidazolesulphonic acid (sold in particular under the trade name “Eusolex 232” byMerck), or disodium phenyl dibenzimidazole tetrasulphonate (sold underthe trade name “Neo Heliopan AP” by Haarmann and Reimer),

[0066] triazine derivatives, in particular anisotriazine (sold under thetrade name “Tinosorb S” by Ciba Specialty Chemicals), ethylhexyltriazone (sold in particular under the trade name “Uvinul T150” byBASF), diethylhexyl butamido triazone (sold under the trade name“Uvasorb HEB” by Sigma 3V) or 2,4,6-tris(diisobutyl4′-amino-benzalmalonate)-s-triazine,

[0067] benzotriazole derivatives, in particular drometrizole trisiloxane(sold under the name “Silatrizole” by Rhodia Chimie) or methylenebisbenzotriazolyl tetramethylbutylphenol (sold in the solid form underthe trade name “Mixxim BB/100” by Fairmount Chemical or in themicronized form in aqueous dispersion under the trade name “Tinosorb M”by Ciba Specialty Chemicals),

[0068] anthranilic derivatives, in particular menthyl anthranilate (soldunder the trade name “Neo Heliopan MA” by Haarmann and Reimer),

[0069] imidazoline derivatives, in particular ethylhexyldimethoxybenzylidene dioxoimidazoline propionate,

[0070] benzalmalonate derivatives, in particular polyorganosiloxanecomprising benzalmalonate functional groups (sold under the trade name“Parsol SLX” by Hoffmann-LaRoche),

[0071] 4,4-diarylbutadiene derivatives, in particular 1,1′-dicarboxy(2,2′-dimethyl-propyl)-4,4-diphenylbutadiene,

[0072] and their mixtures.

[0073] The organic photoprotective agents which are more particularlypreferred are selected from the group consisting of ethylhexylsalicylate, ethylhexyl methoxycinnamate, octocrylene,phenylbenzimidazole sulphonic acid, benzophenone-3, benzophenone-4,benzophenone-5, 4-methylbenzylidene camphor, terephthalylidene dicamphorsulphonic acid, disodium phenyl dibenzimidazole tetrasulphonate,2,4,6-tris(diisobutyl 4′-aminobenzalmalonate)-s-triazine, anisotriazine,ethylhexyl triazone, diethylhexyl butamido triazone, methylenebisbenzotriazolyl tetramethylbutylphenol, drometrizole trisiloxane,1,1′-dicarboxy (2,2′-dimethylpropyl)-4,4-diphenylbutadiene, and theirmixtures.

[0074] The inorganic photoprotective agents may be selected from thegroup consisting of pigments or alternatively nanopigments (mean size ofthe primary particles: generally between 5 nm and 100 nm, preferablybetween 10 nm and 50 nm) formed from coated or uncoated metal oxides,such as, for example, titanium oxide (amorphous or crystalline in therutile and/or anatase form), iron oxide, zinc oxide, zirconium oxide orcerium oxide nanopigments, which are all UV photoprotective agents wellknown per se. Conventional coating agents are, furthermore, aluminaand/or aluminium stearate. Such nanopigments formed from coated oruncoated metal oxides are disclosed in particular in Patent ApplicationsEP 518 772 and EP 518 773.

[0075] The photoprotective agents are generally present in thecompositions according to the invention in proportions ranging from 0.1to 20% by weight with respect to the total weight of the composition andpreferably ranging from 0.2 to 15% by weight with respect to the totalweight of the composition.

[0076] In another advantageous aspect of the invention, the compositionused can additionally comprise at least one other depigmenting oranti-pigmentation active principle in addition to the hydrophilic activeprinciple mentioned above.

[0077] The depigmenting or anti-pigmentation agents capable of beingincorporated in the composition according to the present inventioninclude, for example, the following compounds: kojic acid; ellagic acid;arbutin and its derivatives, such as those disclosed in ApplicationsEP-895 779 and EP-524 109; hydroquinone; aminophenol derivatives, suchas those disclosed in Applications WO 99/10318 and WO 99/32077, inparticular N-cholesteryloxycarbonyl-para-aminophenol andN-ethyloxycarbonyl-para-aminophenol; iminophenol derivatives, inparticular those disclosed in Application WO 99/22707;L-2-oxothiazolidine-4-carboxylic acid or procysteine, and its salts andesters; ascorbic acid and its derivatives, in particular ascorbylglucoside and magnesium ascorbyl phosphate; 4-butylresorcinol orlucinol; thiourea and its derivatives; calcium D-pantetheinesulphonate;and plant extracts, in particular extracts of manzanita, of liquorice,of mulberry and of skullcap, without this list being limiting.

[0078] The composition according to the invention can be applied to, forexample, the skin, hair, including body hair, eyelashes, nails or lips.It can thus be used in a cosmetic treatment process for depigmentingand/or lightening the skin and/or hair, including body hair, comprisingthe application of the composition according to the invention to theskin and/or hair, including body hair

[0079] In an alternative form, the composition according to theinvention can be used for the manufacture of a dermatologicalpreparation comprising an aqueous phase which is intended to depigmentthe skin and/or hair, including body hair.

[0080] The examples which follow serve to illustrate the inventionwithout, however, exhibiting a limiting nature. The compounds are,depending on the situation, cited according to chemical names oraccording to CTFA (International Cosmetic Ingredient Dictionary andHandbook) names.

EXAMPLES Example 1

[0081] Accelerated Storage Test.

[0082] The aim of this test is to study the decomposition of anoxidation-sensitive hydrophilic active principle after storing for twomonths at 45° C. Various solutions were prepared and their compositionsare collated in the following table: TABLE I Compositions (in Solution Awater) (Control) Solution B Solution C Solution D Ascorbic acid 15% 15%15% 15% Polymer 1 —  1% — — Polymer 2 — —  1% — Polymer 3 — — —  1%

[0083] All the solutions are brought to pH 6 with 8.9 mol/l KOH.

[0084] The percentages of the polymers are given as active material.

[0085] Polymer 1: Vinylpyrrolidone/vinylimidazole (50/50) copolymer soldunder the reference Luvitec VPI 55K72W of BASF (Weight-average molecularmass 1.2×10⁶).

[0086] Polymer 2: Vinylpyrrolidone/vinylimidazole (50/50) copolymer soldunder the reference Luvitec VPI 55K18P of BASF (Weight-average molecularmass 10 000).

[0087] Polymer 3: Polyvinylpyrrolidone sold under the reference Kollidon12PF of BASF (Weight-average molecular mass 3 000).

[0088] The degree of decomposition measured is given by the ratio:

(C₀-C_(2 months))/C₀

[0089] with C₀ concentration of ascorbic acid at t=0 and C_(2 months)the concentration of ascorbic acid at t=2 months, under the conditionsindicated in the above table.

[0090] The concentration of ascorbic acid is determined by the HPLCtechnique (LaChrom Merck system). The analytical conditions are asfollows:

[0091] Column: Lichrosphere100 RP18 (250 mm)

[0092] Eluent: 0.1 M phosphate buffer, pH 2.1

[0093] Flow rate: 1 ml/min

[0094] Detection at 257 nm

[0095] Dilution of the sample such that the concentration of ascorbicacid is between 0.05 and 1 mg/ml.

[0096] The results obtained are collated in the following Table II:TABLE II Degree of decomposition after 2 months at 45° C. (in %) underair, amber glass bottle under nitrogen, aluminium flask Solution A 4319.4 Solution B 10.8 1 Solution C 23.4 4.5 Solution D 35.8 15.7

[0097] It is found, from Table II, that the stability of ascorbic acidis improved in the presence of Polymer 1 and Polymer 2 of the invention,even in the presence of atmospheric oxygen, in comparison with thecontrol. It is also found that the N-vinylpyrrolidone homopolymer aloneis not sufficient to effectively stabilize the ascorbic acid solution.As the polymers mentioned are hydrophilic, it will be sufficient to addthem to an aqueous ascorbic acid solution to stabilize the ascorbicacid.

Example 2

[0098] Demonstration of the Activity With Regard to the Dendricity ofMelanocytes:

[0099] The aim of this test is to show the effect of the combination ofascorbic acid with a polymer or copolymer according to the invention onadjusting the melanogenesis of human keratinocyte-melanocyte cocultures.

[0100] Method: The cells are treated from inoculation with the ascorbicacid/vinylpyrrolidone-vinylimidazole copolymer combinations for 7 days.

[0101] Observations:

[0102] The melanocytes are labelled using the NK1beteb antibody (greencolouring), which recognizes the melanosomes at every stage ofmaturation. The nuclei of all the cells, melanocytes and keratinocytes,are stained using propidium iodide (red colouring).

[0103] Results:

[0104] In the absence of the ascorbicacid/vinylpyrrolidone-vinylimidazole copolymer combinations, themelanocytes in cocultures are highly dendritic. The pigment is visiblytransferred to the neighbouring keratinocytes.

[0105] In the presence of the ascorbicacid/vinylpyrrolidone-vinylimidazole copolymer combinations, themajority of the melanocytes show a reduced dendricity and somemelanocytes become bipolar.

[0106] For a higher concentration, the majority of the melanocytes arebipolar and the amount of pigment transferred to the keratinocytes isreduced.

Example 3

[0107] O/W Anti-Blemish Cream

[0108] The following composition is prepared in a way conventional to aperson skilled in the art. A₁ Sorbitan tristearate 0.7 g Polyethyleneglycol (40 EO) stearate 1.6 g Cetyl alcohol 3.2 g Glyceryl mono-, di-,tripalmitate/stearate 2.4 g Myristyl myristate 2 g Liquid fraction ofkarite butter 2 g Preservative 0.2 g A₂ Cyclopentadimethylsiloxane 15 gB Demineralized water 60.53 g Glycerol 3 g Ascorbic acid 5 g 50%Potassium hydroxide 3.07 g Vinylpyrrolidone/vinylimidazole copolymer 1 gPreservative 0.2 g C Fragrance 0.1 g

[0109] This cream which is soft on application makes it possible toreduce pigmentary blemishes and confers good stability on ascorbic acid.

Example 4

[0110] Depigmenting Gel

[0111] The following composition is prepared in a way conventional to aperson skilled in the art. Demineralized water 78.58 gPolyacrylamide/C₁₃-C₁₄ isoparaffin/Laureth-7 2 g (Sepigel 305) Siliconeoil 10 g Ascorbic acid 5 g 50% Potassium hydroxide 3.07 gVinylpyrrolidone/vinylimidazole copolymer 1 g Preservative 0.25 gSequestering agent 0.1 g

[0112] A fresh gel is obtained, which gel makes it possible to combatcutaneous blemishes and in which gel ascorbic acid has good stability.

[0113] The above description of the invention, as illustrated byExamples, allows one of ordinary skill in the art to lighten the skinand/or hair, including body hair, using a composition comprising, in aphysiologically acceptable medium comprising an aqueous phase, at leastone oxidation-sensitive hydrophilic active principle selected from thegroup consisting of, e.g., ascorbic acid and its derivatives, and atleast one non-crosslinked N-vinylimidazole polymer or copolymer, thesaid active principle and the said polymer or copolymer both being inthe aqueous phase. Also made available is the use of a combinationcomposed of at least one oxidation-sensitive hydrophilic activeprinciple selected from the group consisting of ascorbic acid and itsderivatives and of at least one non-crosslinked N-vinylimidazole polymeror copolymer in the aqueous phase of a cosmetic composition as agent forlightening the skin and/or hair, including body hair. In addition, thisinvention makes available the use of at least one oxidation-sensitivehydrophilic active principle selected from the group consisting ofascorbic acid and its derivatives and of at least one non-crosslinkedN-vinylimidazole polymer or copolymer for the preparation of adermatological composition comprising an aqueous phase which is intendedto depigment the skin and/or hair, including body hair. Similarly madeavailable is the use of a combination composed of at least oneoxidation-sensitive hydrophilic active principle selected from the groupconsisting of ascorbic acid and its derivatives and of at least onenon-crosslinked N-vinylimidazole polymer or copolymer in the aqueousphase of a cosmetic composition as agent for lightening the skin and/orhair, including body hair, and the use of at least oneoxidation-sensitive hydrophilic active principle selected from the groupconsisting of ascorbic acid and its derivatives and of at least onenon-crosslinked N-vinylimidazole polymer or copolymer for thepreparation of a dermatological composition comprising an aqueous phasewhich is intended to depigment the skin and/or hair, including bodyhair. A preferred embodiment of the invention fully described and madeavailable herein is a method for lightening the skin and/or hair,comprising applying thereto a composition comprising a physiologicallyacceptable medium comprising an aqueous phase; at least oneoxidation-sensitive hydrophilic active principle selected from the groupconsisting of ascorbic acid and its derivatives, and at least onenon-crosslinked N-vinylimidazole polymer or copolymer, the activeprinciple and the polymer or copolymer both being present in the aqueousphase.

[0114] French patent application 0115375 is hereby incorporated byreference, as are all references, texts, documents, standards,applications, patents, etc., mentioned above.

[0115] Also incorporated herein by reference are the following U.S.applications, all filed Nov. 27, 2002, where the present application islisted for information only: U.S. Ser. No. . . . (Atty. Docket230634US0) U.S. Ser. No. . . . (Atty. Docket 230608US0) U.S. Ser. No. .. . (Atty. Docket 230616US0) U.S. Ser. No. . . . (Atty. Docket230614US0) U.S. Ser. No. . . . (Atty. Docket 230615US0)

1. A method for lightening the skin and/or hair, comprising applying tohair and/or skin to be lightened a composition comprising: aphysiologically acceptable medium comprising an aqueous phase; at leastone lightening oxidation-sensitive hydrophilic active principle selectedfrom the group consisting of ascorbic acid and its derivatives presentin an amount sufficient to lighten the skin and/or hair, and: at leastone non-crosslinked N-vinylimidazole polymer or copolymer, the at leastone active principle and the at least one polymer or copolymer bothbeing present in the aqueous phase.
 2. The method according to claim 1,wherein the hydrophilic active principle is selected from the groupconsisting of ascorbic acid esters and salts.
 3. The method according toclaim 1, wherein the hydrophilic active principle is selected from thegroup consisting of 5,6-di-O-dimethylsilylascorbate, dl-α-tocopheryldl-ascorbyl phosphate potassium salt, magnesium ascorbyl phosphate andsodium ascorbyl phosphate.
 4. The method according to claim 1, whereinthe oxidation-sensitive hydrophilic active principle is ascorbic acid.5. The method according to claim 1, wherein said composition comprises anon-crosslinked copolymer that is a combination of the N-vinylimidazolewith N-vinylpyrrolidone and/or N-vinylcaprolactam subunits.
 6. Themethod according to claim 1, wjerein said composition comprises anon-crosslinked N-vinylimidazole/N-vinylpyrrolidone copolymer.
 7. Themethod according to claim 1, wherein the composition comprises anon-crosslinked copolymer selected from the group consisting of avinylpyrrolidone/vinylimidazole (50/50) copolymer having aweight-average molar mass of 1 200 000 and avinylpyrrolidone/vinylimidazole (50/50) copolymer having aweight-average molar mass of 10
 000. 8. The method according to claim 1,wherein the molar ratio of N-vinylimidazole unit equivalent in saidpolymer or copolymer to the oxidation-sensitive hydrophilic activeprinciple varies between 0.004 and
 16. 9. The method according to claim8, wherein the molar ratio of the N-vinylimidazole unit equivalent tothe oxidation-sensitive hydrophilic active principle varies between 0.01and
 1. 10. The method according to claim 1, wherein the polymer orcopolymer is present in said composition in a concentration of from 0.1to 5% by weight of the aqueous phase.
 11. The method according to claim10, wherein the polymer or copolymer is present at a concentration ofbetween 0.1 and 2% by weight of the aqueous phase.
 12. The methodaccording to claim 1, wherein the polymer or copolymer has a molarfraction of N-vinylimidazole units of between 0.1 and
 1. 13. The methodaccording to claim 12, wherein the polymer or copolymer has a molarfraction of N-vinylimidazole units of between 0.4 and 0.9.
 14. Themethod according to claim 1, wherein the composition further comprises adepigmenting or anti-pigmentation agent which is different from theoxidation-sensitive hydrophilic active principle.
 15. The methodaccording to claim 14, wherein the depigmenting or anti-pigmentationagent is selected from the group consisting of kojic acid; ellagic acid;arbutin and its derivatives; hydroquinone; aminophenols; iminophenols;L-2-oxothiazolidine-4-carboxylic acid or procysteine, and its salts andesters; 4-butylresorcinol or lucinol; thioureas; calciumD-pantetheinesulphonate; ascorbyl glucoside, magnesium ascorbylphosphate; and plant extracts.